Modern wireless communication devices typically include a baseband section, an RF transmitter section and an RF receiver section. In broad terms, when the wireless device operates in transmit mode, the baseband section processes signals before they are modulated and up-converted for transmission by the RF transmitter section at a higher frequency than employed in the baseband section. When the wireless device operates in receive mode, the baseband section processes signals after they have been down-converted by the RF receiver section. The transmitter section and receiver section together form an RF transceiver section. The baseband section and the RF transceiver section may be fabricated on separate integrated circuits (IC's) that are interfaced with one another. The RF transceiver section includes a frequency synthesizer that controls the transmit and receive frequencies of the communication device.
Many contemporary communication devices transmit information in a series of signal bursts. For example, time division multiple access (TDMA) communications systems employ a series of TDMA bursts to transmit information. If a communication transmitter were allowed to immediately power up to full power at the beginning of a burst and to immediately power down at the end of a burst, such a transmitter could generate undesired radio frequency products in the radio spectrum. These undesired products could potentially interfere with the operation of other communication devices. It is thus desirable to ramp up and ramp down the power of the transmitter at the beginning and end of a burst in a controlled manner to avoid generating undesired radio frequency products.
Industry standards and/or government regulations may place strict limits on the amount of power that a transmitter may transmit, for example during a signal burst. In some transmitters, setting the output power to a prescribed power limit may take multiple steps. The more time that such output power calibration consumes, the more expensive a particular communication device becomes to manufacture in the communication device factory. It is desirable that communication devices be manufactured by a process which includes output power calibration that employs a minimal a number of steps.
What is needed is a wireless communication device including an improved output calibration feature which addresses the problems discussed above.